Research Methods
Steps in Psychological Research
Experimental Design
Variables – IV and DV
Operational Hypothesis
Extraneous Variables
Participants
Study Design Dot Points
- experimental research: construction of research
hypotheses; identification of operational
independent and dependent variables;
identification of extraneous and potential
confounding variables including individual
participant differences, order effects,
experimenter effect, placebo effects; ways of
minimising confounding and extraneous variables
including type of experiment, counterbalancing,
single and double blind procedures, placebos;
evaluation of different types of experimental
research designs including independent-groups,
matched-participants, repeated-measures;
reporting conventions
Steps in Psychological Research

Scientific research involves using a research
method to collect information relating to a
particular research area, then organising the
results and reaching conclusions from that
data

This is often planned and conducted in a
particular way known as the scientific method

If the scientific method is not followed then
it is difficult to reach valid conclusions
regarding your research
1. Identify the research problem

The first step is to identify an area of
interest or a topic to be researched

A literature search will aid the researcher in
determining what prior research has been
conducted and what areas of the topic might
need further research

This will allow the researcher to propose a
research question which can be investigated
and researched
2. Formulate a hypothesis

A hypothesis is a testable prediction of the
relationship between two or more
variables

It is usually based in prior knowledge of
the area or topic to be researched and is
formulated prior to the conduction of the
research
3. Design the method

The method needs to be designed based around the
hypothesis and what you determine as being the best way to
test it

The research method will depend upon the topic and the
hypothesis

It must be decided what participants will be studies, how
many, and how they will be allocated to the study

The method to collect data also needs to be determined

Ethical considerations also need to be taken into account
here
4. Collect the data

This step involves collecting the data which
will be used to test the hypothesis

Psychology uses many different data
collection methods such as questionnaires,
observations, interviews, and physiological
recordings to obtain data

Once again the method of data collection
will depend upon the study
5. Analysing the data

The data then needs to be collated and
organised into a meaningful display

This may involve collating large amounts
of data and summarising into tables,
graphs etc in order to better determine if
the hypothesis is supported or rejected
based upon the results
6. Interpret the data

The data then needs to be interpreted and
explained so conclusions can be formed

A conclusion is a judgement about what the
results of an investigation mean

Statistical tests can be used to help
determine the significance of the results and
whether the hypothesis is supported or
rejected based upon the research
7. Report the findings

The final step is to report the findings to
others who may be interested in the
research

A strict format is followed to report the
findings of psychological research

This step is important as it allows others to
examine the validity of your research and
allow them to replicate the study if needed
The first thing I would like you to do now is
to create a flow-chart demonstrating how
psychological research is conducted
Make sure you include some important
points about each step and why they are
important
Experimental Design

An experiment is used to test a cause-effect
relationship between two or more variables

Research can be conducted to determine if
one variable (a possible cause) has an effect
on another variable

Write down two examples of where you
think there could be a cause-effect
relationship between two variables
Variables
A variable is any factor which can change
or vary over time
 Below write down 5 examples of a
variable – it can be anything which varies
over time

Independent Variable

The independent variable (IV) is the
variable in the research which is
manipulated or changed by the researcher
to measure its affects on the participants
responses or results

It is called the independent variable
because the researcher can independently
vary it is some way during the research
Dependent Variable

The dependent variable (DV) shows any
effects of the IV and is expected to change
as a result of manipulation of the IV

It is called the dependent variable because
whether or not it will change and the way in
which it changes is dependent on the IV

In the cause-effect relationship, the IV is the
possible cause, while changes in the DV are
the possible effects
Recognising the IV and the DV

It is important that you are able to
recognise the IV and the DV in particular
scenarios

Using the following research question,
determine the IV and the DV…

Does smoking marijuana affect driving
performance?
Recognising the IV and the DV

In this particular scenario the IV is
whether or not the participant has
smoked marijuana while the DV is the
participants driving performance

Driving performance is dependent on
whether or not the individual has smoked
marijuana or not
Recognising the IV and DV

It is important you are able to recognise
what variable constitutes the IV and the
DV in a research question

It is handy to have a memory device to
enable you to remember how to
recognise the IV and DV

What you wear depends on the weather

What you wear (the DV) is dependent on
the weather (the IV)
Worksheet

Complete the worksheet
◦ Independent and Dependent Variables
◦ For each of the research questions, see if you
can determine the IV and the DV
IV and DV

Simple experiments use one IV with two values or
levels (usually referred to as an experimental condition
and a control condition)

In the experimental condition the IV is present or
and tested while in the control condition the IV is
removed

The control provides a comparison for the
experimental condition where the IV was present

Without a control it would not be possible to
determine if the IV has caused a change in the DV
Operational Hypothesis

As we have previously seen, a hypothesis
is a testable prediction between two or
more variables

For our research question example…

It is predicted that smoking marijuana will
affect driving performance
Operational Hypothesis

But how do we know the levels or values
which will be used in our variables?

The previous research hypothesis doesn’t
tell us who will be studied or what values
the variables will be
Operational Hypothesis

Looking at our research hypothesis again – It is
predicted that smoking marijuana will affect driving
performance

How do we know how much marijuana is smoked,
and when? How will we determine what driving
performance will be measured? Who are we
measuring?

An operational hypothesis expresses the research
hypothesis in terms of how the experimenter will
determine the presence and levels of the variables
under investigation – how the experimenter is going
to put the hypothesis into operation and who it will
be studying
Operational Hypothesis

We therefore need to operationalise our
variables – that is show how they will be in
operation, as well as showing what the
population is which will be studied



Variables which need to be operationalised
IV – Whether or not marijuana is smoked
DV – Driving performance

We also need to determine what population
we will be studying
Operational Hypothesis

An example of how we could operationalise our
variables…

IV – Smoking marijuana: Smoking one joint containing
500mg of pure marijuana (not mixed with tobacco)
20 minutes before taking a driving test

DV – Driving performance: % score on the Vic Roads
“Are you ready?” driving simulator

And the population…

Males aged 18-25years of age
Operational Hypothesis

Now we can formulate our operational
hypothesis…

It is predicted that males aged 18-25 years of
age who have smoked marijuana (smoking
one joint containing 500mg of pure
marijuana 20 minutes before taking a driving
test) will perform worse on a driving test
(obtain a lower % score on the Vic Roads
“Are you Road Ready?” driving simulator)
compared to participants who have not
smoked marijuana.
Worksheet

The best way to learn how to create an
operational hypothesis is to do it yourself

Complete the worksheet “Writing an
operational hypothesis”
How can you remember what you
need to include in an operational
hypothesis?

A good way to remember what you need
to include is to use the acronym…
I
P
O
D

-
Extraneous Variables

Extraneous variables are any variable other
than the independent variable that can cause
a change in the DV affect the results of the
research in an unwanted way

Think back to the previous research
scenario regarding smoking marijuana
affecting driving performance, what could
some possible extraneous variables be in
this research question?
Extraneous Variables

It is important that the influence of any
extraneous variables are minimised or eliminated

If an extraneous variable is not controlled for it
can cause confusion in the results and the
researcher cannot be sure if any change in the DV
has come about as a result of the IV

When an extraneous variable is uncontrolled and
causes confusion in the results it is referred to as
a confounding variable
Extraneous Variables

For our research question (does smoking
marijuana affect driving performance?)
what are some possible extraneous
variables which could cause a change in
the DV?
Methods to Control Extraneous
Variables

Participant selection

Experimental design

Placebo effects (single-blind)

Experimenter effects (double-blind)
Participant Selection

When we conduct research we may want to
draw conclusions which are relevant to a
particular group or groups of people

This group is referred to as the population

It is very rare for research to be conducted
on every member of a population therefore
we use a representation of that population
known as the sample
Participant Selection

It is important that the sample is an accurate representation of the
population

To achieve this accurate representation researchers use random
sampling and stratified random sampling

Random sampling is a procedure in which every member of the
population has an equal chance of being selected

Stratified random sampling involves dividing the population in subgroups based on the value of a certain variable which may be
confounding, the sample is then taken randomly from each group
so as to create a sample with an equal proportion as each group
exists in the population

This could be any personal variable such as age, gender, weight etc
Participant Selection

For example if the population of people who did yoga in FTG
was 5000 people, then it is very unlikely that there would be
50-50 male to female

In fact (to use a generalisation) there is probably a great deal
more females which means if we took a random sample it is
unlikely to be a complete representation of the population

We can stratify the population so as to include equal
proportions of the gender as they appear in the population

Stratified random sampling is very time consuming as you
need to identify the relevant factors which need to be
stratified and the proportions in the population calculated